Engine misfires occur in internal combustion engines when the fuel fails to entirely combust. Misfires are undesirable because misfires reduce fuel efficiency and engine power output. In addition, misfires can also contribute to emission levels, as uncombusted fuel released to the atmosphere contains higher levels of particulate matter and Volatile Organic Compounds (“VOC”) than combusted fuel.
Previous attempts to detect misfires have focused on certain characteristics that result from misfires, such as changes in crankshaft speed, wheel speed, and the like. These attempts seek to detect misfires based on events external to the engine and filter the inputs and perform algorithmic computations on the data to reduce or eliminate the false detections of misfire. Such attempts receive data input, such as crankshaft speed, filter and modify the data based on the algorithm, and determine a misfire based on the modified data using a comparison based on earlier data. These approaches often feature “filter switching” techniques in which a series of filters are applied to the data, and the filtered output serves as a basis for the misfire determination. Filter switching techniques rely on filter coefficient swapping and buffer purging, each of which require time, computational power, and/or destruction of data.
However, prior methods of detecting misfires, while eliminating false positives, rely on a certain level of data to test each input. This data is generally developed in real time, and during a startup operation, such as the first few crankshaft revolutions on startup, the data is ineffective to determine a misfire accurately. Government regulations require monitoring misfires no later than the end of the second crankshaft revolution after engine start, and identify which cylinder generated the misfire. However, previous solutions have required use of monitor buffers to accumulate a sufficient data store for determination of the misfire.
Therefore, it would be desirable to provide a method and system of detecting a misfire that would overcome the aforementioned and other disadvantages.